Buggy code:
public class JMeterMenuBar extends JMenuBar implements LocaleChangeListener { private static final Logger log = LoggingManager . getLoggerForClass ( ) ; private JMenu fileMenu ; private JMenuItem file_save_as ; private JMenuItem file_selection_as ; private JMenuItem file_revert ; private JMenuItem file_load ; private List file_load_recent_files ; private JMenuItem file_merge ; private JMenuItem file_exit ; private JMenuItem file_close ; private JMenu editMenu ; private JMenu edit_add ; private JMenuItem edit_remove ; private JMenu runMenu ; private JMenuItem run_start ; private JMenu remote_start ; private JMenuItem remote_start_all ; private Collection remote_engine_start ; private JMenuItem run_stop ; private JMenuItem run_shut ; private JMenu remote_stop ; private JMenuItem remote_stop_all ; private Collection remote_engine_stop ; private JMenuItem run_clear ; private JMenuItem run_clearAll ; private JMenu optionsMenu ; private JMenu lafMenu ; private JMenuItem sslManager ; private JMenu helpMenu ; private JMenuItem help_about ; private String [ ] remoteHosts ; private JMenu remote_exit ; private JMenuItem remote_exit_all ; private Collection remote_engine_exit ; public JMeterMenuBar ( ) { } public void setFileSaveEnabled ( boolean enabled ) { } public void setFileLoadEnabled ( boolean enabled ) { } public void setFileRevertEnabled ( boolean enabled ) { } public void setProjectFileLoaded ( String file ) { } public void setEditEnabled ( boolean enabled ) { } public void setEditAddMenu ( JMenu menu ) { } public void setEditMenu ( JPopupMenu menu ) { } public void setEditAddEnabled ( boolean enabled ) { } public void setEditRemoveEnabled ( boolean enabled ) { } public void createMenuBar ( ) { } private void makeHelpMenu ( ) { } private void makeOptionsMenu ( ) { } private JMenu makeLanguageMenu ( ) { JMenu languageMenu = new JMenu ( JMeterUtils . getResString ( "choose_language" ) ) ; languageMenu . setMnemonic ( 'C' ) ; JMenuItem english = new JMenuItem ( JMeterUtils . getResString ( "en" ) , 'E' ) ; english . addActionListener ( ActionRouter . getInstance ( ) ) ; english . setActionCommand ( CHANGE_LANGUAGE ) ; english . setName ( Locale . ENGLISH . getLanguage ( ) ) ; languageMenu . add ( english ) ; <START_BUG> JMenuItem japanese = new JMenuItem ( JMeterUtils . getResString ( "jp" ) , 'J' ) ; <END_BUG> japanese . addActionListener ( ActionRouter . getInstance ( ) ) ; japanese . setActionCommand ( CHANGE_LANGUAGE ) ; japanese . setName ( Locale . JAPANESE . getLanguage ( ) ) ; languageMenu . add ( japanese ) ; JMenuItem norway = new JMenuItem ( JMeterUtils . getResString ( "no" ) , 'N' ) ; norway . addActionListener ( ActionRouter . getInstance ( ) ) ; norway . setActionCommand ( CHANGE_LANGUAGE ) ; norway . setName ( "no" ) ; languageMenu . add ( norway ) ; JMenuItem german = new JMenuItem ( JMeterUtils . getResString ( "de" ) , 'G' ) ; german . addActionListener ( ActionRouter . getInstance ( ) ) ; german . setActionCommand ( CHANGE_LANGUAGE ) ; german . setName ( Locale . GERMAN . getLanguage ( ) ) ; languageMenu . add ( german ) ; JMenuItem french = new JMenuItem ( JMeterUtils . getResString ( "fr" ) , 'F' ) ; french . addActionListener ( ActionRouter . getInstance ( ) ) ; french . setActionCommand ( CHANGE_LANGUAGE ) ; french . setName ( Locale . FRENCH . getLanguage ( ) ) ; languageMenu . add ( french ) ; JMenuItem chineseSimple = new JMenuItem ( JMeterUtils . getResString ( "zh_cn" ) ) ; chineseSimple . addActionListener ( ActionRouter . getInstance ( ) ) ; chineseSimple . setActionCommand ( CHANGE_LANGUAGE ) ; chineseSimple . setName ( Locale . SIMPLIFIED_CHINESE . toString ( ) ) ; languageMenu . add ( chineseSimple ) ; JMenuItem chineseTrad = new JMenuItem ( JMeterUtils . getResString ( "zh_tw" ) ) ; chineseTrad . addActionListener ( ActionRouter . getInstance ( ) ) ; chineseTrad . setActionCommand ( CHANGE_LANGUAGE ) ; chineseTrad . setName ( Locale . TRADITIONAL_CHINESE . toString ( ) ) ; languageMenu . add ( chineseTrad ) ; JMenuItem spanish = new JMenuItem ( JMeterUtils . getResString ( "es" ) ) ; spanish . addActionListener ( ActionRouter . getInstance ( ) ) ; spanish . setActionCommand ( CHANGE_LANGUAGE ) ; spanish . setName ( "es" ) ; languageMenu . add ( spanish ) ; JMenuItem turkish = new JMenuItem ( JMeterUtils . getResString ( "tr" ) ) ; turkish . addActionListener ( ActionRouter . getInstance ( ) ) ; turkish . setActionCommand ( CHANGE_LANGUAGE ) ; turkish . setName ( "tr" ) ; languageMenu . add ( turkish ) ; return languageMenu ; } private void makeRunMenu ( ) { } private void makeEditMenu ( ) { } private void makeFileMenu ( ) { } public void setRunning ( boolean running , String host ) { } public void setEnabled ( boolean enable ) { } private void getRemoteItems ( ) { } public void localeChanged ( LocaleChangeEvent event ) { } private void updateMenuElement ( MenuElement menu ) { } }

Fix:
JMenuItem japanese = new JMenuItem ( JMeterUtils . getResString ( "ja" ) , 'J' ) ;